The present disclosure relates to a video-based method and system for efficient vehicle detection/localization in still images obtained from a fixed video camera. The disclosed method and system are applicable to parking space management. However, it is to be appreciated that the present exemplary embodiments are also applicable to other like applications.
One challenge that parking management companies face while managing on-street parking is an accurate detection of available spaces. Conventional methods for detecting vehicle occupancy in parking spaces include non-video based sensing solutions. For example, “puck-style” or in-ground sensors, shown in FIG. 1, typically use magnetometer readings to sense when a vehicle is detected in a parking space. Ultrasonic sensors, as shown in FIG. 2, operate by sending and receiving high frequency sonic waves and evaluating a parking area based on processing a signal that has been reflected back to the ultrasonic sensor. The detected information is wirelessly communicated to interested parties. One disadvantage associated with these sensor-based methods is a high cost for installation and maintenance of the sensors. In addition, the maintenance or replacement of a sensor may reduce parking efficiency if a parking space is made unavailable for the service work.
Another method being explored is a video-based solution. This method is shown in FIG. 3 and includes monitoring on-street parking spaces using non-stereoscopic video cameras. The cameras output a binary signal to a processor, which uses the data for determining occupancies of the parking spaces.
One shortcoming of both technologies is that they are designed for, and limited to, single-space parking configurations. On-street parking can be provided in two different configurations. A first configuration is shown in FIG. 4 and includes single-space parking, also known as stall-based parking, in which each parking space is defined in a parking area by clear boundaries. The parking spaces are typically marked by lines (shown in phantom) that are painted on the road surface to designate one parking space per vehicle. The second configuration is shown in FIG. 5 and includes multi-space parking, in which a long section of street is designated as a parking area to accommodate multiple vehicles. In this configuration, there are no pre-defined boundaries that designate individual parking stalls, so a vehicle can park at any portion extending along the parking area. In many instances, the multi-space parking configurations are more efficient because, when spaces are undesignated, drivers aim to fit more vehicles in a multi-space parking area having a same length as a single-space parking area.
At present, many departments of transportation are transitioning from single-space parking configurations to the multi-space parking configurations. Cities are eliminating parking meters and single-space parking configurations to reduce maintenance and other costs. The sensor-based methods are best suited for parking areas where painted lines typically demark a defined parking space for a single vehicle. However, an incorporation of the sensor-based methods for use in multi-space parking configurations is conceptually difficult and expensive to continue. Accordingly, this transition reduces a need for in-ground and other sensor-based methods.
Given the comparatively lower cost of a video surveillance camera, a video-based solution offers a better value if it is incorporated into a management scheme for monitoring multi-space parking configurations, as well as some applications of single-space street parking. Another advantage of a video-based solution is that one video camera can typically monitor and track several parking spots, whereas multiple sensors may be needed to reliably monitor one parking space in the single-space parking configuration. Additionally, maintenance of the video cameras is likely to be less disruptive than maintenance of in-ground sensors.